As first discovered by The Verge, the recently released iOS 12.1 update brings Apple’s controversial “performance management feature” to the iPhone X, iPhone 8, and iPhone 8 Plus for the first time. With this tool, Apple can dynamically throttle the devices (i.e. slow them down) as the battery degrades in order to stop random shutdowns.

With a low battery state of charge, a higher chemical age, or colder temperatures, users are more likely to experience unexpected shutdowns. In extreme cases, shutdowns can occur more frequently, thereby rendering the device unreliable or unusable. For iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7, and iPhone 7 Plus, iOS dynamically manages performance peaks to prevent the device from unexpectedly shutting down so that the iPhone can still be used. This performance management feature is specific to iPhone and does not apply to any other Apple products. Starting with iOS 12.1, iPhone 8, iPhone 8 Plus, and iPhone X include this feature, but performance management may be less noticeable due to their more advanced hardware and software design.